This invention relates to an improved crop conditioner roll such as is used in a mower-conditioner or the like.
As is well known, a mower-conditioner, such as shown in U.S. Pat. No. 3,797,207, also assigned to the assignee herein, includes a pair of crop conditioner rolls between which crop material passes after it is severed from the field, the crop material being deposited on the ground in a windrow after it leaves the conditioning rolls. The conditioning rolls act to crush and/or crimp the stems of the crop material as it passes between the rolls, and, as is well known, the crushing or crimping of the stems accelerates the drying or curing of the stems, reducing the amount of time that the crop must lay in the field before it can be safely stored in bales, haystacks, or the like.
The mower-conditioner of more recent vintage, the conditioner rolls have been made of molded elastomeric material, typically rubber, and have included lugs or ribs that mesh with spaces between the lugs or ribs on the opposite roll. U.S. Pats. 3,732,670 and 3,513,645 illustrate molded rubber rolls typical of those on machines currently being marketed.
Such molded rolls conventionally include a tubular steel core with a rubber body molded onto the core. The process currently being utilized to manufacture said rolls has required relatively high pressures that has necessitated the use of a relatively thick walled tubular core, which has both increased the cost of the roll and increased the weight of the machine wherein the roll is utilized. Also it has been found that the molding process frequently deforms the tubular core, and keeping such rolls within acceptable limits in regard to straightness has been a problem.
To overcome such problems, it has been proposed that the rolls be made of cast polyurethane, wherein the molding process does not require the high pressures. This has permitted the use of thinner walled tubing for the core and also a thinner layer of material on the core, since there is no longer deformation of the core during the molding process. However, the polyurethane is substantially more expensive than rubber, and the material costs still present a problem for such rolls.